Simplify closure a bit

Commons/Sources/Commons/FoundationCommons.swift

@@ -51,7 +51,7 @@ public extension RandomAccessCollection where Index == Int {
     return result.map { $0! }
   }
 
-  func groupedRanges<T: Equatable>(
+  func groupedRangesOriginal<T: Equatable>(
     with marker: (Index, Element) -> T
   ) -> [CountableClosedRange<Index>] {
     if self.isEmpty { return [] }
@@ -86,6 +86,42 @@ public extension RandomAccessCollection where Index == Int {
 
     return result
   }
+
+  func groupedRanges<T: Equatable>(
+    with marker: (Element) -> T
+  ) -> [CountableClosedRange<Index>] {
+    if self.isEmpty { return [] }
+    if self.count == 1 { return [self.startIndex...self.startIndex] }
+
+    var result = [CountableClosedRange<Index>]()
+    result.reserveCapacity(self.count / 2)
+
+    let inclusiveEndIndex = self.endIndex - 1
+    var lastStartIndex = self.startIndex
+    var lastEndIndex = self.startIndex
+    var lastMarker = marker(self.first!) // self is not empty!
+    for i in self.startIndex..<self.endIndex {
+      let currentMarker = marker(self[i])
+
+      if lastMarker == currentMarker {
+        if i == inclusiveEndIndex {
+          result.append(lastStartIndex...i)
+        }
+      } else {
+        result.append(lastStartIndex...lastEndIndex)
+        lastMarker = currentMarker
+        lastStartIndex = i
+
+        if i == inclusiveEndIndex {
+          result.append(i...i)
+        }
+      }
+
+      lastEndIndex = i
+    }
+
+    return result
+  }
 }
 
 public extension NSRange {

Commons/Tests/CommonsTests/SwiftCommonsTest.swift

@@ -24,7 +24,7 @@ class ArraySliceTest: XCTestCase {
       Dummy(value: 2, marker: false),
 
       Dummy(value: 3, marker: false),
-    ][1...3].groupedRanges { _, element in element.marker }
+    ][1...3].groupedRanges { element in element.marker }
 
     expect(grouped).to(equal(
       [
@@ -43,7 +43,7 @@ class ArraySliceTest: XCTestCase {
       Dummy(value: 3, marker: true),
 
       Dummy(value: 3, marker: true),
-    ][1...3].groupedRanges { _, element in element.marker }
+    ][1...3].groupedRanges { element in element.marker }
 
     expect(grouped).to(equal(
       [
@@ -61,7 +61,7 @@ class ArraySliceTest: XCTestCase {
       Dummy(value: 2, marker: true),
 
       Dummy(value: 3, marker: true),
-    ][1...2].groupedRanges { _, element in element.marker }
+    ][1...2].groupedRanges { element in element.marker }
 
     expect(grouped).to(equal(
       [
@@ -81,7 +81,7 @@ class ArraySliceTest: XCTestCase {
       Dummy(value: 1, marker: true),
 
       Dummy(value: 1, marker: true),
-    ][1...5].groupedRanges { _, element in element.marker }
+    ][1...5].groupedRanges { element in element.marker }
 
     expect(grouped).to(equal(
       [
@@ -103,7 +103,7 @@ class ArraySliceTest: XCTestCase {
       Dummy(value: 1, marker: true),
 
       Dummy(value: 1, marker: true),
-    ][1...5].groupedRanges { _, element in element.marker }
+    ][1...5].groupedRanges { element in element.marker }
 
     expect(grouped).to(equal(
       [
@@ -121,7 +121,7 @@ class ArraySliceTest: XCTestCase {
       Dummy(value: 0, marker: true),
 
       Dummy(value: 0, marker: true),
-    ][1...1].groupedRanges { _, element in element.marker }
+    ][1...1].groupedRanges { element in element.marker }
 
     expect(grouped).to(equal(
       [
@@ -138,7 +138,7 @@ class SwiftCommonsTest: XCTestCase {
       Dummy(value: 1, marker: false),
       Dummy(value: 2, marker: false),
       Dummy(value: 3, marker: false),
-    ].groupedRanges { _, element in element.marker }
+    ].groupedRanges { element in element.marker }
 
     expect(grouped).to(equal(
       [
@@ -154,7 +154,7 @@ class SwiftCommonsTest: XCTestCase {
       Dummy(value: 1, marker: false),
       Dummy(value: 2, marker: false),
       Dummy(value: 3, marker: true),
-    ].groupedRanges { _, element in element.marker }
+    ].groupedRanges { element in element.marker }
 
     expect(grouped).to(equal(
       [
@@ -168,7 +168,7 @@ class SwiftCommonsTest: XCTestCase {
     let grouped = [
       Dummy(value: 0, marker: true),
       Dummy(value: 1, marker: true),
-    ].groupedRanges { _, element in element.marker }
+    ].groupedRanges { element in element.marker }
 
     expect(grouped).to(equal(
       [
@@ -184,7 +184,7 @@ class SwiftCommonsTest: XCTestCase {
       Dummy(value: 1, marker: false),
       Dummy(value: 1, marker: true),
       Dummy(value: 1, marker: true),
-    ].groupedRanges { _, element in element.marker }
+    ].groupedRanges { element in element.marker }
 
     expect(grouped).to(equal(
       [
@@ -202,7 +202,7 @@ class SwiftCommonsTest: XCTestCase {
       Dummy(value: 1, marker: true),
       Dummy(value: 1, marker: false),
       Dummy(value: 1, marker: true),
-    ].groupedRanges { _, element in element.marker }
+    ].groupedRanges { element in element.marker }
 
     expect(grouped).to(equal(
       [
@@ -216,7 +216,7 @@ class SwiftCommonsTest: XCTestCase {
   func testArrayGroup6() {
     let grouped = [
       Dummy(value: 0, marker: true),
-    ].groupedRanges { _, element in element.marker }
+    ].groupedRanges { element in element.marker }
 
     expect(grouped).to(equal(
       [

NvimView/Sources/NvimView/NvimView+Draw.swift

@@ -213,7 +213,7 @@ extension NvimView {
   ) -> [AttributesRun] {
     rowRange.map { row in
       self.ugrid.cells[row][columnRange]
-        .groupedRanges(with: { _, cell in cell.attrId })
+        .groupedRanges(with: { cell in cell.attrId })
         .compactMap { range in
           let cells = self.ugrid.cells[row][range]
 

NvimView/Sources/NvimView/Typesetter.swift

@@ -102,7 +102,7 @@ final class Typesetter {
         return [FontGlyphRun(font: font, glyphs: glyphs, positions: positions)]
       }
 
-      let groupRanges = glyphs.groupedRanges { _, element in element == 0 }
+      let groupRanges = glyphs.groupedRanges { element in element == 0 }
       let groupRuns: [[FontGlyphRun]] = groupRanges.map { range in
         if glyphs[range.lowerBound] == 0 {
           let nvimUtf16Cells = unichars[range].map { [$0] }

NvimView/Support/DrawerPerf/PerfTester.swift

@@ -75,7 +75,7 @@ class PerfTester {
     let ugrid = self.ugrids[index]
     return rowRange.map { row in
       ugrid.cells[row][columnRange]
-        .groupedRanges(with: { _, cell in cell.attrId })
+        .groupedRanges(with: { cell in cell.attrId })
         .compactMap { range in
           let cells = ugrid.cells[row][range]